Congress has ordered the Obama administration to explain who created its "talking points" on the deadly September 11 attack in Benghazi, Libya, and who omitted the CIA's early conclusion that terrorists were involved.

Senator Dianne Feinstein, the Senate Intelligence Committee chairman, said on NBC's "Meet the Press" on Sunday that she does not believe the White House tried to cover up the terrorism link.

But Sen Feinstein said it is unclear why the attack was initially described as it was, and that the Obama administration must provide more information.

Government officials at first characterised it as arising from a spontaneous demonstration over an inflammatory Internet video.

Image Caption:UN Ambassador Susan Rice

UN Ambassador Susan Rice used those first talking points in talk-show interviews days after the attack, and has since come under criticism from Republican lawmakers who say she deliberately misled the public.

Last week President Barack Obama fiercely defended Ms Rice, who is seen as a front-runner to succeed Hillary Clinton as Secretary of State.

"But for them to go after the UN ambassador? Who had nothing to do with Benghazi? And was simply making a presentation based on intelligence that she had received? To besmirch her reputation is outrageous."

Subsequent information made clear the Benghazi attack was a pre-planned terrorist strike.

CIA officials, including former Director David Petraeus, told Congress last week they had determined quickly that al-Qaida was involved but wanted to keep that information classified.

Lawmakers have been interviewing top intelligence and national security officials in trying to determine what the intelligence community knew before, during and after the attack.